This is basically a clinical support contract to supply high quality viral diagnostic studies of immuno-suppressed cancer patients at the Baltimore Cancer Research Center and the Pediatric Oncology Branch, DCT, NCI. Certain types of viruses infect such compromised hosts with a high degree of frequency, causing dangerous or fatal viral infections. Data obtained by means of this contract will provide specific indentification of the infecting viruses to enable the use of optimal therapy. Specific viral studies to be utilized are viral isolation and identification of materials from lesions or body fluids, viral antibody level determination of acute and convalescent sera and electron microscopy studies.